1. Technical Field of the Invention
The present invention relates to a cooling system for a computer and particularly, to a system for cooling a computer such as a personal computer by means of the system management (SM) bus.
2. Description of the Prior Art
Increase in temperature inside a computer apparatus can be prevented by using a cooling fan which introduces external air into the computer apparatus. Thus, the computer apparatus such as a personal computer maintains its performances, in spite of heat generated by electronic parts such as integrated circuits.
However, a ceaseless operation of the cooling fan is noisy and consumes much electric power. Therefore, it is desirable to suppress the temperature increase inside the computer apparatus, preventing noise and saving power consumption.
In JP 10-275033 A (1998), a cooling fan is switched off, when the inside temperature becomes lower than a prescribed temperature, by using a temperature sensor, while the cooling fan is switched on, when the temperature inside the computer apparatus reaches another prescribed temperature.
Further, in JP 4-340111 A (1992), the cooling fan is not only switched on/off, but also its rotational speed is controlled. The cooling system as disclosed in JP 4-340111 A (1992) is shown in FIG. 5. Temperature sensor 21 detects the temperature inside the computer apparatus. Memory 23 stores table 27 which describes a relation between the inside temperature and the rotational speed of the cooling fan. The rotational speed of cooling fan 26 is controlled by rotational speed controller, referring to table 27.
However, the cooling system as shown in FIG. 5 has a disadvantage that connection wires are increased and a size of the computer apparatus becomes large, because the connection wires and cables are required for all of the cooling system elements.
Therefore, an object of the present invention is to make it feasible to employ the SM bus in order to control the cooling fan inside a computer, thereby preventing noise, saving power consumption, and providing small sized computers.
A first cooling system for a computer of the present invention comprises an SM (System Management) bus controller for controlling the components on SM buses of the computer, a fan rotation speed control IC provided with an SM bus interface, and a temperature sensor provided with another SM bus.
A second cooling system for a computer of the present invention comprises a temperature sensor for measuring the temperature inside a computer; an SM bus controller for setting up prescribed temperatures and register values corresponding those temperatures, for reading out the temperature from the sensor through an SM bus, and for notifying a fan rotation speed control IC of the register value corresponding the measured inside temperature through another SM bus; and a fan rotation speed control IC for supplying a cooling fan with a reference voltage defined by a reference voltage signal corresponding to a register value notified by the SM bus controller through the SM bus. Here, the fan rotation speed control IC sets up register values and reference voltage signal corresponding to the register values.
A third cooling system for a computer of the present invention includes a specific type of the fan rotation speed control IC as described in the second cooling system. Concretely, the specific type of the fan rotation speed control IC comprises: a fan rotation set-up register for setting up register values and reference voltage signal corresponding to the register values, and for outputting a digital reference voltage signal corresponding to the register value, when the register value is notified from the SM bus controller through the SM bus; a D/A converter for converting the digital reference voltage signal into an analogue reference voltage signal; and a voltage source circuit comprising an operational amplifier and a transistor for inputting the analogue reference voltage signal, for generating a reference voltage corresponding to the analogue reference voltage signal, and for supplying a cooling fan with the generated reference voltage.
A fourth cooling system for a computer of the present invention is characterized in that the fan rotation speed control IC of the above-mentioned second and third cooling system is placed inside the cooling fan.
A fifth cooling system of a computer of the present invention is characterized in that a cooling fan is switched on/off. Concretely, the fifth cooling system comprises an SM bus controller for controlling the components on SM buses of the computer, a fan on/off control IC provided with an SM bus interface, and a temperature sensor provided with another SM bus.
A sixth cooling system for a computer of the present invention switching on/off a cooling fan, by using SM bus and SM bus controller. Concretely, the sixth cooling system of the present invention comprises a temperature sensor for measuring the temperature inside a computer; an SM bus controller for setting up prescribed temperatures and register values corresponding to those temperatures, for reading out the temperature from the sensor through an SM bus, and for notifying a fan on/off control IC of the register value corresponding to the measured inside temperature through another SM bus; and a fan on/off control IC for supplying a cooling fan with a reference voltage defined by a reference voltage signal corresponding to a register value notified by the SM bus controller through the SM bus. Here, the fan on/off control IC sets up register values and reference voltage signal corresponding to the register values.
A seventh cooling system for a computer of the present invention includes a specific type of the fan on/off control IC as described in the sixth cooling system. Concretely, the specific type of the fan on/off control IC comprises: a fan on/off set-up register for setting up register values and reference voltage signal corresponding to the register values, and for outputting a digital reference voltage signal corresponding to the register value, when the register value is notified from the SM bus controller through the SM bus; a D/A converter for converting the digital reference voltage signal into an analogue reference voltage signal; and a voltage source circuit comprising an operational amplifier and a transistor for inputting the analogue reference voltage signal, for generating a reference voltage corresponding to the analogue reference voltage signal, and for supplying a cooling fan with the generated reference voltage.
An eighth cooling system for a computer of the present invention is characterized in that the fan on/off control IC of the above-mentioned sixth and seventh cooling system is placed inside the cooling fan.
According to the present invention, the number of signal wires are reduced, due to the employment of SM bus. Further, according to the present invention, the computer apparatus including its cooling system becomes small-sized, due to the employment of SM bus controller which controls not only the cooling system, but also the computer.
Further, according to the present invention, the mounting area is reduced, because FAN rotation speed control IC is mounted inside the FAN.